export function getRandomArrayElements(arr, count) {
    var shuffled = arr.slice(0),
        i = arr.length,
        min = i - count,
        temp,
        index; //只是声明变量的方式, 也可以分开写
    while (i-- > min) {
        //console.log(i);
        index = Math.floor((i + 1) * Math.random()); //这里的+1 是因为上面i--的操作  所以要加回来
        temp = shuffled[index]; //即值交换
        shuffled[index] = shuffled[i];
        shuffled[i] = temp;
        //console.log(shuffled);
    }
    return shuffled.slice(min);
}